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Soldering a Steel Bolster On To a Brass Liner

Posted: Thu Jan 16, 2020 7:18 pm
by Jeffinn
I’m working on a Boker electrician knife and during disassembly one of the bolsters popped off. It looks like it had a very small spot weld holding it in place. I soldered it back on and it seems to be attached well but I’m wondering if this is the right approach.
I could drill it and install a small steel pin but that may end up being visible on the top when finished.
Anyone here have any experience with this?
Thanks.
Jeff

Re: Soldering a Steel Bolster On To a Brass Liner

Posted: Thu Jan 16, 2020 7:29 pm
by orvet
I am working on a Boker right now that popped one of the bolsters. My bolsters were nickel silver and soldered easily.
I glued the stag and hafted it to the bolsters and to the liner but when I picked it up to do a test fitting a a front bolster fell off of one half and a rear bolster fell off the other. I didn't want to pop the stag loose, solder on two bolsters and hope I had everything in the right place. Instead I chose to pin the bolsters. I did that from the inside making sure I did not drill all the way through the bolster.

Let me get some pictures and I will bring it back and post them and show you what it looks like, because I haven't got it put back together yet.

I also decided I'm not going to work on anymore German knives because of the way they barely attach the bolsters. :x

Re: Soldering a Steel Bolster On To a Brass Liner

Posted: Thu Jan 16, 2020 7:34 pm
by Jeffinn
Thanks Dale, I appreciate it!
Jeff

Re: Soldering a Steel Bolster On To a Brass Liner

Posted: Thu Jan 16, 2020 7:38 pm
by Meridian_Mike
If the bolsters are steel then a piece of a coat hanger or a small nail should work as a pin. If the bolsters are steel, they are probably mind steel so the properties should match (I would think).


Dang, it sure is bad to hear about your German knife experiences Dale.... makes me paranoid.

:shock:

Re: Soldering a Steel Bolster On To a Brass Liner

Posted: Fri Jan 17, 2020 6:07 am
by Bill DeShivs
Soldering the bolster is as good an approach as any.

Re: Soldering a Steel Bolster On To a Brass Liner

Posted: Fri Jan 17, 2020 11:08 am
by mrwatch
when you say soldered them, you do not say how? soft radio solder and flux won't last. Plumbing solder with acid paste may hold okay. The low heat silver solder with liquid flux may hold quite well. But you will need a small torch flame or Prest-O-Lite torch tip. using care to not remove the temper and with out the scales on it. I would wrap the blade with a damp cloth

Re: Soldering a Steel Bolster On To a Brass Liner

Posted: Fri Jan 17, 2020 6:27 pm
by Bill DeShivs
Bolsters have been soft-soldered on knives for a hundred years. Maybe it won't last...

Re: Soldering a Steel Bolster On To a Brass Liner

Posted: Fri Jan 17, 2020 7:17 pm
by stockman
Bill DeShivs wrote: Fri Jan 17, 2020 6:27 pm Bolsters have been soft-soldered on knives for a hundred years. Maybe it won't last...
Bill, years ago I repaired Gas meters. Some of them had parts soldered together. We used the old irons heated in a little furnace,and 50-50 solder. Would this work on knives?

Harold

Re: Soldering a Steel Bolster On To a Brass Liner

Posted: Sat Jan 18, 2020 2:56 am
by Bill DeShivs
A small torch works better than soldering irons or guns.

Re: Soldering a Steel Bolster On To a Brass Liner

Posted: Sat Jan 18, 2020 11:40 pm
by orvet
Jeffinn wrote: Thu Jan 16, 2020 7:34 pm Thanks Dale, I appreciate it!
Jeff
Jeff,
Here are the insides of the bolsters that fell off of the Boker folding Hunter. I attached them using 1/16" pins.
I drilled the 1/16" hole into the bolster and then used a tiny ball burr to widen out the bottom of the hole so the pin could mushroom out and hold tight.

Boker Bolster Repair.jpg

I used two pins in the front bolster which was much wider and thicker but only one in the rear bolster.
They are quite secure.

Re: Soldering a Steel Bolster On To a Brass Liner

Posted: Sun Jan 19, 2020 12:46 am
by Jeffinn
That sounds easy enough, thanks Dale!
I never thought about using a small ball burr to widen the hole at the bottom for the pin. That’s definitely a technique I’ll keep in my pocket for future reference.
Jeff

Re: Soldering a Steel Bolster On To a Brass Liner

Posted: Sun Jan 19, 2020 2:10 am
by Reverand
That is probably much more secure now than when it left the factory.
I agree with soldering them if there are no scales mounted yet, and pinning if there are. I even mounted some with a thin layer of epoxy, knowing that the pivot pin did more to hold them on than the epoxy.
The only problem that I can forsee is trying to match the German silver nickel. Theirs are often a slightly darker color than the US rods that I use for pins.

EDIT: I just re-read where Dale said not to drill all the way through. Makes much more sense to me now!

Re: Soldering a Steel Bolster On To a Brass Liner

Posted: Sun Jan 19, 2020 11:50 pm
by orvet
Reverand wrote: Sun Jan 19, 2020 2:10 am I agree with soldering them if there are no scales mounted yet, and pinning if there are. I even mounted some with a thin layer of epoxy, knowing that the pivot pin did more to hold them on than the epoxy.
I actually worked on one German knife and the bolsters were made from a curved sheet of nickel silver, so they were hollow underneath. There was no solder, no pin, no method of attaching the bolsters to the liners other than the pressure exerted on the bolsters by the pivot pins. As soon as I cut the pins to take the knife apart, the bolsters fell right off. I was able to repair the knife and get it back together but it was really a pain!

Soldering a Steel Bolster On To a Brass Liner

Posted: Sun Feb 02, 2020 11:14 am
by Douglasvab
You can drill and tap it. I would tap it for 2-56 threads, minimum. The bolster isnt heat treated and doesnt need to be annealed. Its 416SS, engravable.

Drill and tap all the way through the liner, as well. Then flush the screw with the backside of the liner to keep it from scraping the blade.

That should do it
Let me know if you have any questions.

Re: Soldering a Steel Bolster On To a Brass Liner

Posted: Mon Feb 03, 2020 10:21 am
by orvet
Douglasvab wrote: Sun Feb 02, 2020 11:14 am You can drill and tap it. I would tap it for 2-56 threads, minimum. The bolster isnt heat treated and doesnt need to be annealed. Its 416SS, engravable.
Actually most bolsters are nickel silver as is the Boker folding hunter I posted.
If you drill through the bolster you will have a steel screw showing in a nickel silver bolster.
Even with steel bolsters, most of the older ones are carbon steel and most machine screws today I have seen are stainless steel, that will also show up in the bolster.

Re: Soldering a Steel Bolster On To a Brass Liner

Posted: Mon Feb 03, 2020 3:09 pm
by Meridian_Mike
Douglasvab wrote: Sun Feb 02, 2020 11:14 am You can drill and tap it. I would tap it for 2-56 threads, minimum. The bolster isnt heat treated and doesnt need to be annealed. Its 416SS, engravable.

Drill and tap all the way through the liner, as well. Then flush the screw with the backside of the liner to keep it from scraping the blade.

That should do it
Let me know if you have any questions.
Welcome to the forum....

That is a heck of a first post.
:shock:

Re: Soldering a Steel Bolster On To a Brass Liner

Posted: Thu Oct 15, 2020 8:15 pm
by Jeffinn
orvet wrote: Thu Jan 16, 2020 7:29 pm I am working on a Boker right now that popped one of the bolsters. My bolsters were nickel silver and soldered easily.
I glued the stag and hafted it to the bolsters and to the liner but when I picked it up to do a test fitting a a front bolster fell off of one half and a rear bolster fell off the other. I didn't want to pop the stag loose, solder on two bolsters and hope I had everything in the right place. Instead I chose to pin the bolsters. I did that from the inside making sure I did not drill all the way through the bolster.
I also decided I'm not going to work on anymore German knives because of the way they barely attach the bolsters. :x
I just ran across this today on a Tree Brand knife I was working on. Three of the bolsters fell off and the fourth one was easily removed by hand. Like you, I had already shaped and hafted the bone handles.
The original attachment for these bolsters seems to be glue of some sort which works okay for a one time installation. It’s a cheap alternative to soldering them on, I’m not a fan. It’s the first time Ive seen it.
Like Dale, I’m no longer going to work on Boker knives.
Jeff

Re: Soldering a Steel Bolster On To a Brass Liner

Posted: Thu Oct 15, 2020 9:07 pm
by Doc B
Dale, that's a neat idea!
Douglasvab...that's sounds like a good way to go, too, if you had the technology available. Welcome to AAPK.

Re: Soldering a Steel Bolster On To a Brass Liner

Posted: Fri Oct 16, 2020 2:29 am
by Bill DeShivs
Bolsters on the German knives were not glued on. Most were soldered.
Some modern ones are spot-welded.
Regardless, the way to do a PROPER repair is to take the handles off, solder the bolster back on, and put the handle back on.